Fluid operated gear shifting mechanism



Sept. 12, 1944. w. G. HOELSCHER 2,357,952

- FLUID OPERATED GEAR SHIFTING MECHANISM Original Filed July 18, 1940Patented Sept. 12, '1944 rum) OPERATED can. smr'rlNG' MECHANISM WilliamG. Hoels cher, Cincinnati, Ohio, assign- 'or to The American Tool Works.Company, Cincinnati, 01110, a corporation of Ohio Original applicationJuly 18, 1940, Serial'No.

Divided and this application August 22, 1942, Serial No. 455,761

'1 Claims, (01. 192-35) This invention relates to fluid operated gearshifting or speed changing mechanism. More particularly, it is directedto a system or circuit arrangement wherein the operations ofpre-selection and shifting are coordinated with the operating means forthe clutch which controls the power connection to the transmission.

It is highly desirable that the operator be able to pre-select thespeed, to which he intends to shift, while the transmission is beingdriven. A system should be so arranged that the operator may select thenext speed regardless of the fact that the transmission is in operation.Further, it should be arranged so that the operator cannot change gearswhile the transmission is coupled to the power source. Also, when theclutch lever is in neutral, it is desirable to hold the shifting valvein place by power after it has been set manually so that there will beample time in which the shift may take place.

Therefore, it has been the object of the present inventor to provide asystem and arrangement of control elements which will produce the aboveresults; that is, will permit the operator to pro-select while the.power is coupled to the transmission, which will permit the actualshift to be made only when the power is disconnected, and which willhold the shift control valve in shifting position when the power isuncoupled so that all the operator need do is to move 'the valve toshift position, whereupon it will be held in shift positionhydraulically until the power which drives the transmission is againconnected.

More particularly, it has been the object of .rotation being effectivefor speed selection and.

the depressive movement being for the purpose of shifting the shiftervalve plunger to shifting position. If the control valve is closed, aswhen the power is coupled, the depressive movement is idle andaccomplishes nothing; but if the valve is open, the depressive movementwill bring about the shift and the oil under pressure will hold theshifting valve plunger in shifting position.

The subject matter set forth and described in this application isdivisional of application Serial No. 346,185 filed July -18, 1940, whichmatured on March 9, 1943, as Patent No. 2,213,- 438. I

Other objects and certain advantages will be more fully apparent from adescription of the drawing in which:

Figure l is a diagrammatic view showing the circuit with the elements ofthe circuit shown in section for illustrating the circulation throughthe present inventor to provide a combination of valves, one of whichcontrols the application of hydraulic pressure from the source toshifting and selector valves, and the others of which are operablethrough a single lever for pre-selection and subsequent shift when thefirst valve is opened following uncoupling of the power, and wherein theshifting valve will be held in shifting position when the control valveis open so as to insure the completion of the shift.

The structure bringing about this result resides in the combination of acontrol valve which permits the application of hydraulic pressure to theshifting valve in such a way as to hold it in shifting position when thecontrol valve is open. In this improved structure, the shifting valvemust be operated manually, as an operation separate and apart from theoperation of setting the selector valve. A lever having a rotating andadepressive movement is utilized, the

the various valves.

- Figure 2 is a face view of the selector dial means and gear shiftcontrol means.

Referring to the drawing, the gear shifting system includes an oil pump5, a shut-off valve 6, a shifting valve 1, a selector valve 8, and gearshifting cylinders 9. The valves are in the circuit in the order named.The shifting power is represented by the oil pressure delivered by thepump to the shifting cylinders. Therefore, with the shut off valveclosed, the gear shifting. system is ineffective.

Although only one gear shifting unit and one gear cluster areillustrated, it is obvious that a plurality may be used. The gearcluster to be shifted is indicated at l0 and is slidably mounted on asplined shaft H. To retain the cluster in engaged or disengagedpositions, the splined shaft is provided with detent means shown indotted lines at l2. The gear shifting unit comprises two cylinders l3and I4, one at each end of a plunger i 5. A yoke l6, engaging a groovein the gear cluster, is pinned to the plunger at i1. Thus, to move thecluster for a desired shift, one cylinder is charged as the other one isexhausted.

The pump 5 draws oil from a sump, indicated at l8, through an intakeline l9, and delivers it under pressure through a line 20 to the shutoffvalve 6. The shut-oil valve is open only when the lever 2!, whichcontrols the forward and reverse clutches (not shown) of the drive meansto the transmission, is in neutral.' Consequently, oil pressure ispermitted to pass the shaftof the control lever 2i.

through the shut-oi! valve to the other valves in the circuit to effecta shift only when the gears in the transmission are entirelydisconnected from the drive means.

The shut-off valve comprises a plunger 22 which slides in a cylinder 23in a casing 24. The plunger. included two grooves. When the valve isclosed, one of the grooves 25 is in communication with the pressure line23 from the pump. At this time, the other groove 26 is in communicationwith the sump through an exhaust line 21-, and the shiiting valve 1,through a line 26. The plunger is under the influence of a coil spring23 which tends to move the plunger to connect the lines 26, 23 throughgroove 25.

The end of the plunger opposite the coil spring is tapered and extendsfrom the casing 24 to contact the face of a cam 33 which is fixed toWhen the control lever is in forward or reverse positions, the highsections 3i of the cam face contact the plunger, thus forcing theplunger back into the casing against the pressure of the coil spring forclosing the valve. When the control lever is in neutral, the low section3la of the cam face contacts the plunger, thus permitting the spring toforce the plunger outwardly to open the valve. i

The shifting valve 1 is controlled by a selector handle 32. It iseilective onlywhen the shutoff valve connects lines 20 and 26. Theshifting valve comprises a body 33 in which a plunger 34 slides, and acasing 35in which the body 33 is rotatively journalled. The body extendsfrom the housing and includes a. gear 36 and a pointer element 31 bothofwhich are formed integrally with or fixed to the body and rotate withit. The selector handle 32 is pivoted on a pin 36 in a. slot 33 in thepointer element. The pivot point is to one side of the center ofrotation adjacent the indicator point. of the pointer element, while thehandle extends diametrically across the axis of rotation of the valve.

-by a boss 46 on the underside of the handle 32.

The plunger 34 has two sections of different diameters. The smallerdiameter is provided with an annular groove. The larger diameter isprovided with two annular grooves 42 and 43. A coil spring 44 undercompression, between the inner end of the plunger and the end of thecasing bore, tends to hold the plunger 34 out against the selectorhandle. When in this position, the groove H in the smaller diametersection of the plunger is in communication with the sump 18 through anexhaust line 45. The groove 42 in the larger diameter section is incommunication with the line 23 from the shut-oi! valve through two ports46 and 41. The groove 43 is in communication with the sump through anexhaust line 46 and with the speed selector valve through a, pressureline 43. When the plunger 34 is in its second position, i. e.,

when the selector handle has been pushed in,'

the exhaust line 45 is closed, line 23 is open to groove 4i through port46 and to line 43 through port 41, and the exhaust-line 46. is closed.The

positions indicated on the dial.

operation or this valve, in relation to the circuit. will be discussedbelow.

As stated above, the plunger 340! the shifting valve 1 has two diiferentdiameters. 'The diiferential exists just beyond the groove 4i. When theplunger is in its out position, the shoulder 53 between the portions ofdifferent diameter abuts a shoulder in the body 33. When the selectorhandle is pushed in, the shoulder:

63 on the plunger is moved between the two ports 46 and 41. Thus, withthe shut-01f valve open, oil pressure is admitted to groove 4i throughport 46. At this time, the exhaust line I 'The gear 36 meshes with agear 5| keyed to the end of a shaft 52. The speed selector valveincludes a rotary valve element. 6i to whichthe shaft 52 is directlyconnected. Gears 36 and 5i are identical. Thus, since gear 36 rotateswith the pointer, the rotary speed selector valve also rotates with thepointer. Naturally, the gear link causes a reverse motion between thetwo, but they maintain relative positions as they rotate. A stationarydial 53 is provided for the pointer, indicating the positions of theselector valve. 1

The rotary selector valve distributes and re-- lieves the oil pressurein the correct shifting cylinders-to shift the gear clusters in thetransmission into the speed corresponding to the This descriptiondiscloses only one such position since the construction of these rotaryvalves is well understood in the art. The rotary valve is journalled ina casing 54 and includes two longitudinal passages, an exhaust passage55 open at all times through a line 56 to the sump, and a pressurepassage 51 open at all times to *the pressure line 43 of the circuit.

The line 49 is in communication constantly with an annular groove 60 inthe periphery of the rotary valve element 6i. A port 62 extends radiallyfrom this groove into the passage 51.

Another port 63 extends radially from this pashaust of cylinder i3 istaking place through port 66.

Operation With the clutch lever 2i in either forward or reverseposition, the shut-off valve 6 is closed and the pressure to theshifting valve 1 is relieved. The operator may now select the speed forhis next operation by setting the pointer 31. After he has selected thenext speed. he can stop, reverse or continue on at the same. speed for anumber of operations without disturbing or affecting the pre-selection,even though the clutch lever 2| is moved into neutral many times duringthis period.

To effect a change, the selector handle 32 must be pushed in while theclutch lever is in neutral. The selector handle is foolproof. If theoperator should, by chance, push the selector handle in while the clutchlever is in either forward or reverse position, the coil spring behindthe plunger 34 would move the plunger out again.

As. an example, let us say that the selector mechanism is set to run atspeed A. The forward clutch is engaged, the shut-off valve is closed,and the selector valve- 8 is still set to align the necessary ports toeffect the shift resulting in speed A. The gear cluster at this time isbeing held in its respective position by the detent l2. While themachine is running at speed A, the operator may set the selectormechanism by turning theselector handle 32 for speed 3. The only changein the circuit takes place in the selector valve 8. Here, the portsnecessary to effect speed B and the ports necessary to disengage thegears of speed A are aligned; If the operator desires to continue atspeed A for several operations, he may do so as long as he does not pushin the selector handle while the clutch control handle is in neutral.

Now, when the operator wants to change to the preselected speed B, hethrows the clutch control lever into neutral, This opens the shutoffvalve 6, directing oil pressure through line 28 to the shifting valve 1.He then pushes in the selector handle to direct the oil pressure throughthe shifting valve to the selector valve. The selector handle remainsin, due to the oil pressure on the differential plunger 34. The oilpressure is directed to theshifting cylinders through the line 49 to theselector valve 8, which had been previously set for speed B. As soon asthe clutch lever is moved out of neutral, the

pressure on the selector valve is relieved and the fluid to said plungerand said selector valve, a

shut-off valve interposed between the source of fluid pressure and theselector valve, a clutch lever controlling the power to the transmissionand adapted to open said shut-off valve when in neutral position, and afluid connection from said source of power to said plunger, controlledby said shut-off valve, and'said'plunger having unbalanced areasaffected by said fluid pressure whereby said plunger is held in gearshifting position when the shut-off valve is open.

2. A fluid operated gear shifting mechanism including gears to becoupled, a gear shifting device, a selector valve, a shifter valve, acontrol lever for controlling the power for driving said gears, a sourceof fluid pressure, a. shut-off valve actuated by said control lever, afluid line ex-' tending. from the source of pressure through the '3. Afluid operated gear shifting mechanism including. a shifting valve,means for supplying fluid under pressure to said shifting valve, saidvalve including a rotatable element and an axially slidable plungerhaving unbalanced areas and mounted in the rotatable element, a leverconnected to the rotatable element for rotation thereof and engageablewith the plunger for translation thereof, an indicator means carried bysaid rotatable element, a selector valve having a transmissionconnection to said rotatable element and a fluid connection to saidshifting valve, gear shifting elements supplied from said selector valvewhereby said selector valve may be set to an appropriate speed byrotation of said rotatable element of said shifter valve and the shiftmay be accomplished by translation of said plunger of said shiftervalve, a lever for controlling power for driving gears of saidtransmission, and a shut-oil valve interposed between said shiftingvalve and means for supplying pressure thereto, said shut-oil valvebeing interconnected with said power controlling lever in openedposition when the lever is in neutral position, the interconnectionbeing arranged to close said valve when said lever is shifted fromneutral whereby fluid is admitted to the shifting valve to hold theplunger thereof in a shifting position by exerting unbalanced pressureon the said unbalanced areas of. said plunger after the plunger is movedinitially through the first named lever for translating it.

4. A fiuidoperated gear shifting mechanism, comprising a shut-oil valve,a shifter valve, a selector valve, means for delivering fluid underpressure through said valves in the order named, a control lever foropening and closing said shut-01f valve, and a lever having a compoundmotionfor operating said selector valve in one motion and said shiftervalve in another inotion; whereby, when said shut-off valve is closed,said selector valve may be reset without flow of fluid to the selectorvalve until the control lever is operated toopen the shut-off valve andthe second lever is operated to open the shifter valve for the selectedshift, and said shifter valve having unbalanced areas therein whereby itismaintained in a position to which it has been moved through said leverhaving compound motion until said shut-off valve is closed.

5. A fluid operated gear shifting mechanism,

comprising a shut-off valve, a shifter valve, a

selector valve, a fluid "operating gear shifting unit, means fordelivering fluid under pressure through said valves'to said unit in theorder named, a control lever controlling the power to the gears to beshifted and adapted to open and close said shut-ofl valve, and a secondlever having a compound motion for operating said selector valve in onemotion and said shifter valve in another motion; whereby, when saidshut-off I valve is closed and although said selector valve is reset,the flow of fluid to the selector valve will not occur until the controllever is operated to open the shut-off valve and the second lever isoperated to open the shifter valve, said shifter valve comprising aspring return plunger having unbalanced areas th'erein subject topressure admitted from said shut-off valve when said plunger is in agear shifting position whereby said valve is maintained in said positionagainst the pressure of said spring until said pressure is relievedthrough closure of said shut-off valve.

6. A fluid operated gear shifting mechanism, comprising a selectorvalve, shifting means for moving said selector valve to selectedpositions for appropriate speed changes, a gear shift control plungeractuated by said shifting means for controlling the flow of shiftingfluid to said selector valve, a source of fluid pressure, a shutoffvalve interposed between the source of fluid pressure and said shiftingplunger, a lever adapted to open said shut-oil? valve when said lever isin neutral position, said lever adapted to control the drive to thetransmission, the gears of which are to be shifted, and a fluidconnection to said plunger, controlled by said shut-off valve, with saidplunger having unbalanced areas subjected to the pressure of fluid fromsaid connection, for holding the plunger in gear shifting position whenthe shut-off valve is open.

7. A fluid operated gear shifting mechanism including gears to becoupled, gear coupling means, a selector valve, a shifter valve, meansfor controlling the power connection to the gears, a source of fluidpressure, a shut-off valve actuated by the power control means, a fluidline extending from the source of pressure through the shut-off valve tothe shifter valve, the selector valve and the gear coupling means, amanually operated shifter valve operating means,

said shifter valve including surfaces normally fective upon the surfacesof unequal areas will hold the shifter valve in gear shifting positionwhen manual pressure on the shifter valve has been relieved.

. WILLIAM G. HOELSCHER.

